Open-topped cargo compartments, such as dump trucks, short vehicle trailers, storage bins and the like, are subject to having material stored therein fall or blow out. This can be particularly dangerous while the compartment is being transported. For instance, if portions of the load fall out onto a roadway (e.g., trucks or trailers hauling sand, gravel, dirt or similar materials), traffic accidents can occur, as well as damage to other vehicles and littering of the roadway. Wind effects can intensify the risk of inadvertent material loss. For instance, lightweight materials, such as plant clippings being taken to a landfill, mulch materials, or harvested plants like cotton, are susceptible to gusty winds, which may blow portions of the contents out of the vehicle or bin.
In many places, laws and regulations require the tops of such containers to be covered before they can be transported on public roadways to prevent material being blown out of the containers. Even where there are no laws regarding covering a load, it is beneficial for the driver to cover the load to reduce the possibility of damage to other property from escaping materials. Thus, tarpaulins are commonly used to cover the loads during transport. In addition, tarpaulins are often used to keep environmentally sensitive materials, such as asphalt, wheat, and the like dry and warm or cool during static storage as well as during transport.
Manually placing a tarpaulin onto an open-top container is both time-consuming and expensive. For this reason, the prior art has provided manual and automated tarpaulin covering systems. A typical manual drive system includes a tarpaulin disposed in a rolled fashion on a roller bar, and a crank box, which is disposed at a height that permits an operator to access and operate the device easily. If the roller is disposed at too great a height to be accessed directly, the covering system may include a chain drive that operatively connects the crank box and the roller bar. In such event, the crank box and roller bar typically are equipped with sprocket gears that engage a chain loop, thereby permitting the operator to roll and unroll the tarpaulin by operation of the crank box. In other embodiments, the crank box includes a crankshaft that is coaxial with the roller or that otherwise engages the roller without using a chain loop. In either case, the tarpaulin typically is normally biased towards its unrolled position, i.e., towards the position in which the tarpaulin covers the contents of the container. Often, the bias is created by way of a pair of spring-biased arms that are operatively connected to an end of the tarpaulin and that are biased towards the rear of the vehicle. The crank box may be equipped with a ratchet mechanism to lock the roller bar in position to prevent the tarpaulin from unrolling under the force of the spring-biased arms. The apparatus further may be provided with a brake system to prevent run-away opening when the ratchet mechanism is unlocked.
U.S. Pat. 5,129,698, to Cohrs at al. purports to disclose a system with lever operated locking and brake means in which the tarp cover system includes pawl and ratchet locking means for locking a tarp roll in a partially or fully rolled-up condition, in combination with dual levers. The levers are initially squeezed by one hand of the operator to release the pawl and ratchet locking means, and are subsequently pivoted by the same hand to brake the unwinding of the cover. The ratchet wheel is mounted on the crank shaft of the operating means, whereby the roller is continuously locked against inadvertent unrolling even when in a partially rolled condition.
The invention seeks to provide an improved covering apparatus. In preferred embodiments, the invention seeks to provide a covering apparatus that is operable using a single operator crankshaft handle, and that permits one-handed operation both to roll and to unroll the cover.